Thousands of people were infected with hepatitis C and HIV in the 1970s and 80s.
Photograph: NHS Blood and Transplant/PA

Theresa May’s inquiry into the contaminated blood scandal appears to be faltering, after key campaign groups said they would boycott an initial meeting because they lack faith in the Department of Health.

At least 10 leading campaign groups and the Haemophilia Society are all refusing to attend a meeting on Thursday to consult them about the establishment of the inquiry, because they do not want the department implicated in the scandal to oversee the process.

Survivors initially welcomed the announcement, while expressing frustration that the decades-long wait for answers had been too long. The contamination took place in the 1970s and 80s, and the government started paying those affected more than 25 years ago.

However, they have become disillusioned with the process already because the health department is involved in the establishment of the inquiry.

Liz Carroll, chief executive of the Haemophilia Society, wrote to May on Wednesday saying the department must not be involved in setting the remit and powers of an inquiry investigating its ministers and officials. She also highlighted the fact that key campaigners and individuals affected by the scandal had not been invited to the meeting.

“I call on you to ensure this inquiry is passed to another department and the meeting cancelled until such time it can be reconvened with adequate notice and to include all those whose voices need to be heard,” she said.

In a joint statement, Tainted Blood, The Forgotten Few, Positive Women, The Contaminated Blood Campaign and others said: “We and our members universally reject meeting with the Department of Health as they are an implicated party. We do not believe that the DH should be allowed to direct or have any involvement into an investigation into themselves, other than giving evidence. The handling of this inquiry must be immediately transferred elsewhere.”

They are backed by Diana Johnson, Labour MP and long-time campaigner for those affected by the tainted blood products, who wrote to the prime minister earlier this week saying the public inquiry should not be dealt with by the health department.

A department source said the meeting would go ahead and some campaigners were still expected to attend.

“We are absolutely committed to a thorough and transparent inquiry,” a health department spokesman said. “To establish the best format and remit, we want to hear as many opinions as possible. Our door is open for anyone who wants to discuss the Inquiry or raise any concerns.”

In her statement last week, May promised the government would talk to the families about the shape the inquiry should take “so we ensure that it is able to provide the answers and the justice that they want and deserve”.

She said the infection of thousands of people, mainly haemophiliacs, was “an appalling tragedy which should simply never have happened”.

“The victims and their families who have suffered so much pain and hardship deserve answers as to how this could possibly have happened,” May said, saying they have been “denied those answers for too long and I want to put that right”.

A recent parliamentary report found around 7,500 patients were infected by imported blood products from commercial organisations in the US, whose paid donors included injecting drug users and prison inmates. More than 2,400 haemophiliacs who received the tainted blood are dead.

Speaking during Johnson’s debate, the junior health minister Philip Dunne said families would be consulted about what type of inquiry would be best but the two most likely options were a judge-led statutory inquiry, or a Hillsborough-type independent panel.

Pressure for an inquiry had grown amid campaigning by Johnson and Andy Burnham, the former Labour MP who is now mayor of Greater Manchester.

In his final speech to the Commons in April, Burnham said he had been contacted by victims and families who believed medical records had been falsified to obscure the scandal, saying there was evidence of “a criminal cover-up on an industrial scale”.

In the 1970s and 80s, 4,689 British haemophiliacs were treated with contaminated blood products. So far, more than half of them have died. The government knew there were risks involved. The patients didn’t. Will they ever get justice?